The present invention relates to robots for cleaning the outer wall surface of buildings or other constructions which has windows, and particularly to robots for cleaning windows of buildings.
Along with modern buildings getting higher and higher, the number of windows provided on the outer surface of these high-rise buildings has been increasing remarkably. In order to keep the windowpanes clean, it is necessary to clean them on a periodical basis.
In the past, windowpanes of high-rise buildings were cleaned mostly by manual operations, where, fox example, a cleaning operator, riding on a gondola hung down from the building rooftop, sprinkled clear water onto the windowpanes and then wiped up the water with a squeegee or the like. But, such traditional manual operations provided very poor cleaning efficiency and also was very dangerous.
As an approach to solve the problems, window cleaning robots have been developed and widely employed today which are capable of cleaning windowpanes in a highly-mechanized or automatic manner. In general, such prior window cleaning robots include working components commonly called gate-type squeegees, which are caused to perform its upward/downward, forward/rearward and tilting movements based on the principle of Cartesian (orthogonal) coordinates.
As shown in FIG. 12, the prior window cleaning of this type comprise a head case c having opposite side portions vertically slidably fitted about two linear guide shafts b, which are secured to a frame a hung down from the rooftop of a building via wire ropes r. To the head case c is connected a pair of motor-driven cylinders d for extending and retracting a wiping squeegee e. The wiping squeegee e and receiving squeegee f are connected to the pistons of the motor-driven cylinders d in such a manner that the two squeegees e and f are movable toward and away from the outer wall surface the building (forward/rearward movement). Each of the opposite side portions is further connected to an endless chain that is wound at its both ends around upper and lower sprocket wheels g and h, and the lower sprocket wheel h is connected to a drive shaft j. The drive shaft j is driven or rotated by a motor k, and rotation of the drive shaft j causes the head case c to move in an upward and downward direction along the linear guide shafts b. Further, to the head case c is fixed another pair of motor-driven cylinders 1 for pivotally moving the squeegee e in a vertical direction. Driving this motor-driven cylinder 1 can change the tilt angle of the wiping squeegee e (titling movement).
The present needs with the window cleaning robots are that they are capable of performing intended cleaning operations accurately; they have high reliability to guarantee non-occurrence of failure, damage etc.; they are small and light enough to substantially reduce the size of a roof car suspending the robot from a rooftop; and they are capable of performing cleaning operations at rapid speed and over a wide area.
However, from such a point of view, the prior art window cleaning robots constructed on the orthogonal coordinates principle are not satisfactory in the following points.
The drive shaft that is provided for vertically moving the head case c securing the two squeegees is subjected to a heavy load imparted from the squeegees e, f and head case c and hence tends to be easily damaged, resulting in poor reliability. To enhance reliability, the drive shaft and drive mechanisms associated with the drive shaft must have an increased size.
In addition, with the prior window cleaning robots, a large amount of dirty water and dirt tends to scatter all over during the window cleaning, and various robot components, drive-power transmission mechanisms in particular, must be completely covered or sealed to prevent failure and rust occurring due to adhesion of the soiled water and dirt. However, in fact, it is difficult to provide such complete sealing because the drive-power transmission mechanisms contain many sliding members. This lack of complete sealing also results in poor reliability.
Further, the drive shaft for vertically moving the head case c tends to be twisted as rotational force is transmitted from the sprocket wheel on one side of the head case c to the sprocket wheel on the other side, and this twist can cause delay in the driving-power transmission, with the result that the squeegees can not be maintained in an accurate horizontal position. This also provides poor reliability.
Furthermore, because separate drive mechanisms are employed to perform the upward/downward, forward/rearward and tilting movements, the number of parts is increased and the entire mechanisms become large in size, so that it is difficult to reduce the size and weight of the robot and hence the roof car hanging the robot.
Moreover, with the prior window cleaning robots based on the orthogonal coordinates principle, the wiping squeegee e, receiving squeegee f, motor-driven cylinders d, 1 are attached to the head case c, and thus an extremely heavy load is imparted to the head case c. This heavy load makes it difficult to increase the operation speed of the head case c. In addition, the drive mechanism for the head case c is comprised of many components such as the chains and drive shafts and forms complicated drive-power transmission channels. This also prevents high-speed operation of the head case c.
It is therefore an object of the present invention to provide an improved outer wall cleaning robot which can effectively avoid problems arising from the use of a drive shaft, such as damage to the drive shaft and can completely seal drive-power transmission mechanisms of the robot and which further achieves reduced weight and high-speed operation of the robot.